Method and system for imaging, diagnosing, and/or treating an area of interest in a patient&#39;s body

ABSTRACT

A method and system for imaging, diagnosing, and/or treating an area of interest in a patient&#39;s body is provided. More particularly, a manually steered “rapid exchange” type catheter for a system for imaging, diagnosing, and/or treating an area of interest in a patient&#39;s body is provided. The catheter comprises a catheter body configured to be introduced to an area of interest in a patient&#39;s body, a device for imaging, diagnosing, and/or treating the area of interest contained within the catheter body, and a manual steering device attached to the imaging, diagnosing, and/or treating device to allow an operator to manually steer the imaging, diagnosing, and/or treating device, wherein the catheter is configured to be mounted on a commercially available guidewire.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method and system for imaging, diagnosing,and/or treating an area of interest in a patient's body.

2. Background of the Related Art

The use of less invasive, catheter-based, intravascular techniques hasbeen developed over several decades and may be considered the preferredmode of treatment for those patients amenable to such treatment.Typically, intravascular procedures, such as angioplasty, atherectomy,and stenting, are preceded by a diagnostic procedure, such asangiography and in some cases IntraVascular UltraSonic (IVUS) imaging.

IVUS imaging can frequently provide additional diagnostic informationover what is readily obtained using a fluoroscope and radio-opaque dyesas in angiography. This stems from the fact that geometric measurementsare based on cross-sectional images not “shadow grams” as in singleplane angiography and by virtue of the high contrast nature of theinteraction of sound with tissue as opposed to the interaction of x-rayswith tissues. Further, the angiogram requires the use of x-ray contrastagents that opacify the blood pool and therefore are not intended toexamine the tissue in the vessel wall, but rather the path of the bloodpool itself.

With almost all modern interventional catheter procedures, aninterventionalist or operator first places a guidewire into a targetanatomy or site, such as a vessel(s), artery, or other body cavity ofdiagnostic or therapeutic interest. The guidewire is used to navigatethe target anatomy in the patient's body prior to the diagnostic ortherapeutic catheter being inserted.

The placement of the guidewire is frequently the most difficult and timeconsuming part of the entire procedure. Consequently, once the guidewirehas been advanced into the target anatomy, the interventionalist oroperator does not want to lose the position of the distal end of theguidewire.

After the guidewire is in place, various diagnostic and therapeuticcatheters, such as balloon catheters, stent deployment catheters,atherectomy catheters, IVUS catheters, and thrombectomy catheters, are“loaded” over the guidewire. The guidewire, so placed, serves as a railalong which catheters can be advanced directly to, and withdrawn from,the target site.

There are two basic categories of catheters that are used in conjunctionwith these guidewires. The first category of catheters is referred to as“Over-The-Wire” (OTW) devices. Catheters in the first category have alumen that extends inside the entire length of the catheter into which aguidewire can be inserted. The second category of catheters is referredto as or “rapid exchange” (RX) catheters. In these catheters, theguidewire only enters into the catheter body near its distal end,instead of entering at the proximal-most end, and extends inside thecatheter body to the distal most end of the catheter where it exits.

There are advantages and disadvantages to both designs. The OTWcatheters allow easy exchange of guidewires should additional cathetersupport, from a stiffer guidewire, or a change in the shape or stiffnessof the guidewire tip be necessary. The RX catheters allow the operatorto more rapidly change from one catheter to another while leaving theguidewire in place, thereby preserving the placement of the guidewiredistal tip, which may have been difficult to achieve. Although“standard” length (typically ˜190 cm) guidewires usually have a proximalextension capability built in (extending the overall length to ˜300 cm),the use of these accessories is cumbersome and can require two sterileoperators.

Typically, ˜190 cm guidewires are required to span a vessel from themost distal anatomy that the interventionalist or operator wishes totreat to the point where the guide catheter, enters the patient's body.The entry point may be located, for example, at the femoral artery in apatient's groin, or on occasion, the radial artery in a patient's arm.If the catheter being loaded over the guidewire is an OTW catheter, theguidewire must be long enough so that the entire length of the OTWcatheter can be slid over the proximal end of the guidewire and yetthere remain some length of the guidewire exposed where it enters thepatient's body. That is, the guidewire for an OTW catheter must beapproximately twice as long as one that is to be used only with RXcatheters, because it must simultaneously accommodate both the lengthinside the patient's body and the length of the OTW catheter. Further,the “threading” of the OTW catheter over the distal or proximal end ofthe guidewire is time consuming, and the added length of the guidewirecan be cumbersome to handle while maintaining sterility.

Since the RX design catheters typically have the guidewire runninginside them for only the most distal ˜1 cm to ˜30 cm, the guidewireemployed need only have a little more than the required ˜1 cm to ˜30 cmafter it exits the patient's body. While the loading of an ˜140 cm OTWcatheter over an ˜280 cm to ˜300 cm guidewire is time consuming andtedious, loading the distal ˜10 cm of an RX catheter over a shorterguidewire is easily done.

However, OTW catheters tend to track the path of the guidewire morereliably than RX catheters. That is, the guidewire, acting as a rail,prevents buckling of the catheter shaft when it is pushed forward fromits proximal end over the guidewire. RX catheters can, however, given asufficiently wide target site, such as a sufficiently wide artery, and asufficiently tortuous guidewire path, buckle as they are advanced alongthe guidewire by pushing on the proximal end of the catheter. Inaddition, when an RX catheter is withdrawn from a patient, the RXportion can pull on the guidewire and cause the guidewire to buckle nearthe point that it exits the proximal end of the RX channel.

There are advantages to both designs. However, when the path of thetarget anatomy, such as a vessel, that is to be imaged is not tootortuous and the location of the target imaging site is not toodifficult to reach, the mono-rail or RX catheters are preferred.

Recently catheters and systems have been developed to visualize andquantify the anatomy of vascular occlusions by using IVUS imaging. IVUStechniques are catheter-based and provide real-time cross-sectionalimages of a target anatomy, such as a vessel lumen, diseased tissue inthe vessel, and the vessel wall. An IVUS catheter includes one or moreultrasound transducers at or near the distal tip of the catheter bywhich images containing cross-sectional information of the vessel underinvestigation can be obtained. IVUS imaging permits accurate geometricmeasurements, visualization of the atherosclerotic plaques, and theassessment of various therapies and complications that may result.

Motor driven, mechanically steered IVUS imaging systems typicallyinclude an arrangement in which a single transducer near the distal endof the catheter is rotated at high speed (up to about 1800 rpm) togenerate a rapid series of ˜360-degree ultrasound sweeps. This isexemplified by U.S. Pat. No. 4,794,931 to Yock, which is herebyincorporated by reference. Such speeds result in generation of up toabout thirty images per second, effectively presenting a real timecross-sectional image of, for example, a diseased vessel or artery.

The transducer assembly is mounted on the end of a drive shaft that isconnected to a motor drive at the proximal end of the catheter.Incorporated into the motor drive, or in some cases separate from themotor drive, is an angle encoder that records the angular position ofthe transducer assembly. The rotating transducer assembly is housed in asheath that protects the vessel or artery from the rapidly spinningdrive shaft. The IVUS imaging catheter is advanced to the region ofinterest using the guidewire RX technique to provide real-timecross-sectional images of the lumen and the vessel or arterial wall atthe desired target site. The presence of a mechanically spinning imagingcore in the center of the IVUS catheter prevents OTW versions of motordriven, mechanically steered IVUS catheters.

There is, however, a commercially available, electronically steered IVUScatheter that does not contain a central spinning imaging core that isamenable to either OTW designs or RX designs. Such a catheter andimaging system is disclosed in U.S. Pat. No. 4,917,097 to Proudian,which is hereby incorporated by reference. The electronically steeredIVUS catheters have a ring of ultrasonic transducers located at thedistal tip of the catheters. Tiny electronic multiplexers located justproximal to the ultrasonic transducers are used to select a subset ofthe ultrasonic transducers. By selecting different sets of adjacentelements, the ultrasonic beam can be electronically rotated inpractically any radial direction around the catheter.

U.S. patent application Ser. No. 11/053,141 (hereinafter the “'141application”), which is hereby incorporated by reference, teaches anovel combined therapy and IVUS catheter that is neither electronicallysteered nor attached to an electric motor and spinning rapidly as inconventional commercially available products. The '141 applicationcovers a manually rotated, OTW IVUS system whereby the operator sweepsout a complete image of, for example, a vessel or a sector of a vesselwhen needed by simply rotating the catheter with his or her hand. Thereare many advantages to such an approach; however, the apparatus astaught in the '141 application, due in part to its combined role intherapy, is not amenable to a rapid exchange design. The catheterdescribed in the '141 application can, with the removal of the RFablation antenna, be employed as a purely diagnostic device in a fashionanalogous to all other commercially available IVUS devices.

In the '141 application, the entire catheter is rotated in order tosweep out an image, and there is no obvious way to make this type ofdevice into an RX catheter. That is, because in an imaging applicationthe entire shaft of the catheter is rotated frequently and if theguidewire were to enter the catheter body say ˜1 cm to ˜3 cm from thedistal end of the catheter as in an IVUS RX design, theinterventionalist or operator would be required to torque both thecatheter body and the external length of the guidewire in order to makean image. Rotating the guidewire and the IVUS catheter frequently tomake IVUS images would potentially damage the vessel wall and causegeometric distortions in the resulting image due to the increasedwind-up and backlash at the distal end of the catheter.

In order to provide for the maximum utility of a manually steered IVUSsystem, there is a need for both an OTW version and a RX version ofcatheter depending on the particular application.

The above references are incorporated by reference herein whereappropriate for appropriate teachings of additional or alternativedetails, features and/or technical background.

SUMMARY OF THE INVENTION

An object of the invention is to solve at least the above problemsand/or disadvantages and to provide at least the advantages describedhereinafter.

The invention is directed to a method and system for imaging,diagnosing, and/or treating an area of interest in a patient's body.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objects and advantages of the invention may be realizedand attained as particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in detail with reference to thefollowing drawings in which like reference numerals refer to likeelements wherein:

FIG. 1 is a schematic diagram of an IVUS imaging system;

FIG. 2 is a side view of an IVUS imaging catheter, which is mechanicallysteered by an electric motor;

FIGS. 3A and 3B are side views of electronically steered prior art IVUScatheters, an OTW design shown in FIG. 3A and a RX design shown in FIG.3B;

FIG. 4 is a side view of an OTW manually steered catheter;

FIG. 5 is a side view of a manually steered RX design IVUS catheteraccording to an embodiment of the invention;

FIG. 6 is a side view of a manually steered RX design IVUS catheteraccording to an embodiment of the invention;

FIG. 7 is a side view of a manually steered RX design IVUS catheteraccording to an embodiment of the invention;

FIG. 8 is a side view of a manually steered RX design IVUS catheteraccording to an embodiment of the invention;

FIG. 9A is a perspective view of a handle rotation mechanism thatincorporates a pullback ratcheting mechanism according to an embodimentof the invention;

FIG. 9B is a perspective view of a drive roller mechanism containedwithin the pullback ratcheting apparatus of FIG. 9B;

FIG. 9C is a perspective view of the handle rotation mechanism of FIG.9A, showing an upper housing portion in place;

FIG. 9D is a perspective view of the handle rotation mechanism of FIG.9A, showing an angle encoder.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention is discussed below using an IVUS system as anexample. However, the systems, catheters, and methods discussed hereinmay be utilized with and for any appropriate system, catheter, and/ormethod for imaging, diagnosing, and/or treating an area of interest onor in a patient's body. Further, the term patient is intended to referto any type of patient, human or animal.

FIG. 1 is a schematic diagram of an IVUS imaging system. The system 1includes a catheter 5, having proximal and distal ends 12, 15. Thedistal end or tip 15 is adapted to be inserted into a patient and isconstructed to be navigable through the patient's vasculature to advancethe distal end 15 to an area or site of interest. The distal tip 15 ofthe catheter 5 carries an ultrasound transducer (not shown). Further,the distal end 15 may also carry an ablation electrode (not shown)adapted to ablate an obstructed portion of a vessel or other bodycavity. The proximal end 12 of the catheter 5 is designed to remainoutside of the patient where it can be associated with an angle encoder80 and can be manipulated by an operator, such as an interventionalistor physician.

The system 1 further includes an electronics module 18 that includescircuitry and software for generating signals for operating the system 1and for receiving and processing signals from resulting ultrasoundechoes, as well as for generating an RF ablation signal if an ablationelectrode is included in the system. A central processing unit 23constructs images from the received ultrasound signals and displays theimages on a monitor 21. The images are generated on demand and arerefreshed in response to operator rotation of the catheter 5. The imagesmay be caused to fade after a predetermined time as a reminder to anoperator to refresh the image by rotating the catheter 5. The centralprocessing unit 23 may comprise, for example, a laptop or desktopcomputer or a dedicated embedded processor. Cables 22, 24 are connectedbetween the angle encoder 80 and the electronics module 18. In thisembodiment, the cable 22 carries incremental angle information that issensed by the angle encoder 80 and cable 24 provides power and ground.Separate cables run from the catheter 5 to the electronics module 18 andcarry ultrasound signals and also RF energy if an ablation electrode isincluded in the system. In an alternate arrangement (not shown),transducer and RF cables from the catheter 5 may plug into a connectorintegrated into the angle encoder 80 and then, after pre-amplifying theultrasound signals, pass the signals through a second connector on theangle encoder 80 to the electronics module 18. This alternatearrangement allows for a shorter catheter cable and, potentially,reduces environmental noise pick-up.

One feature of this system is that the catheter is rotated andmanipulated entirely under manual control of the operator. Similarly, inthe case where an ablation electrode is included in the system 1,initiation of an ablation pulse may be determined by the operatorindependently of any direct connection with the catheter or the systemfor sensing catheter rotation. It should be understood that reference to“manual” with respect to control over the application of ablation energyincludes any arrangement by which the operation, based on judgment as tothe proper location of the ablation electrode, initiates the ablationsequence. Thus, “manual” operation may include a variety ofarrangements, including, mechanically controlled switches, for example,a foot switch, or a voice-operated control or other means by which theoperator can trigger an ablation cycle, for example, by manipulation ofpedal 19.

FIG. 2 is a side view of a prior art mechanically steered IVUS imagingcatheter. This catheter 105 employs a RX design, whereby a guidewire 110enters a catheter body 125 less than ˜3 cm from a distal end or tip 115of the catheter 105 in order to allow an imaging transducer 120 to beplaced as close to the distal end or tip 115 as possible.

This catheter also employs a torque cable 140. The torque cable 140 isgenerally torsionally stiff and yet soft in flexion. The torque cable140 is frequently made of a counter wound spring.

The ultrasonic transducer 120 is mounted in a housing 130 a that allowsthe transducer assembly 130 to be coupled to the torque cable 140. Acoaxial wire 145 carries a transmit pulse to the transducer assembly 130and the resulting pulse echoes back to receiver processing circuits (notshown).

The guidewire 110 passes proximally into the catheter 105 through askive 150 less than ˜3 cm from the distal end 115 of the catheter 105.The guidewire 110 then exits through exit 111 at the distal end 115 ofthe catheter 105.

The torque cable 140 is driven by an electric motor 160. The electricmotor 160 is located at a proximal end 161 of the catheter 105, androtates the torque cable 140 at or around 1800 rpm so as to produce astream of ultrasonic images at ˜30 frames (complete ˜360 degree rotationimages) every second.

Such a product as discussed above has been commercially produced byBoston Scientific and Hewlett-Packard. Similar products are described inBom et al., “Early and Recent Intraluminal Ultrasound Devices,”International Journal of Cardiac Imaging, 4:79-88 (1989), which ishereby incorporated by reference.

FIGS. 3A and 3B are side views of prior art electronically steered IVUScatheters. FIG. 3A shows an OTW design, while FIG. 3B shows an RXdesign. In these catheters 205, 305, the transducer assembly 230, 330and an electronic multiplexing circuit assembly 270, 370 have beenfabricated in the shape of concentric cylinders so as to achieve a dualpurpose of leaving a center of the catheter 205, 305 open for thepassage of a guidewire 210, 310 and placement of the transducer assembly230, 330 as far distally as possible. In the case of electronicallysteered IVUS catheters, there is no need for a torque cable extendingthrough the center of the catheter and therefore, both the OTW designshown in FIG. 3A and the RX design shown in FIG. 3B are easily achieved.

FIG. 4 is a side view of a manually steered OTW IVUS catheter describedin detail in the '141 application. The catheter 405 includes a catheterbody 425, an ultrasound transducer assembly 430, and a guidewire 410.The guidewire 410 exits the catheter body 425 at exit 411. As thecatheter 405 is manually rotated, an angle encoder 480 records anangular position of the catheter 405 and relays the data to imagingprocessing electronics (not shown) so as to associate acoustic echoinformation with the correct (relative) angular orientation. The entirecatheter 405 is intended to be rotated to create an image; consequently,it is not easily amenable to an RX design, which would require theguidewire 410 to pass through a skive in the catheter body 425 and berotated along with the catheter 405.

This OTW design has the advantage of allowing the placement of thetransducer assembly 430 very close to the distal end 415 of the catheter405, as in the case of the electronically steered IVUS transducers shownin FIGS. 3A and 3B. However, it would be advantageous, in terms ofallowing the use of shorter guidewires and more rapid exchanges of theIVUS catheter with other catheters, such as therapeutic catheters, tohave an RX version of a manually steered IVUS imaging system.

FIG. 5 is a side view of a manually steered RX design IVUS catheteraccording to an embodiment of the invention. This embodiment of theinvention provides a manual IVUS catheter with the convenience and timeefficiency of an RX design. Further, in this embodiment, a distal or RXportion 595 of the catheter 505 is relatively short so as to allowplacement of the transducer assembly 530 as close to the distal most end515 of the catheter 505 as practical. Furthermore, an imaging orproximal portion 590 of the catheter 505 is allowed to rotate freely toallow rotational steering of the transducer assembly 530, while thedistal portion 595 of the catheter 505 remains stationary and providesguidewire entry or skive 550 and exit 511. A rotational bearing or joint526 is provided between the distal or RX portion 595 and the imaging orproximal portion 590. The rotational bearing or joint 526 may meet thefollowing criteria: extremely low friction when axially and/orflexurally loaded so as not to cause the distal end or tip 515 to rotateas the proximal portion 590 of the catheter 505 is rotated, short lengthand/or ability to flex so as to minimize the flexural discontinuitybetween the distal or RX portion 595 and the imaging or proximal portion590 to maximize the ability of the distal or RX portion 595 to track theguidewire 510, and sufficient strength to prevent separation of thedistal or RX portion 595.

The rotational bearing or joint 526 is made, in this embodiment, of aplastic on metal joint. The outer bearing member 528, which remainsstationary along with the distal or RX portion 595, may be made of amaterial, such as HMW polyethylene. Different grades of the samematerial may then be used to form the distal or RX portion 595. Usingdifferent grades of the same material allows the flexural and frictionalproperties to be optimized and allows the materials to be heat joined byvarious means known in the art. Alternatively, the outer bearing member528 may be made of a low friction material, such as Teflon, mechanicallyand/or adhesively bonded to the tip materials.

The inner bearing member 527, which is attached to the imaging orproximal portion 590, may be made of a highly polished metallicmaterial, such as stainless steel. The imaging or proximal portion 590may be constructed of materials known in the art or catheter design andmanufacture, such as single or multiple durometer polymer extrusions,wire reinforced extrusions, stainless steel wire braided shafts, plainand machined hypodermic tubings, and combinations of the foregoing usedto tailor the torsional and flexural properties to optimize the torquetransmission and flexibility of the catheter.

FIG. 6 is a side view of a manually steered RX IVUS catheter accordingto another embodiment of the invention. The embodiment of FIG. 5 issimilar to the embodiment of FIG. 4 but includes a safety plug 646. Theembodiment of FIG. 6 may include a rotational bearing, such as thatshown in FIG. 5, in addition to the safety plug 646, or may include onlythe safety plug 646 to rotatably connect the distal or RX portion 695 tothe imaging or proximal portion 690. Where tests have been conductedwhich confirm that the safety plug has sufficient tensile strength toprevent separation of the distal or RX portion 695 from the imaging orproximal portion 690, the rotational bearing may not be necessary. Theembodiment shown in FIG. 6 shows the safety plug 646, which is attached,for example, by being welded or adhered, to the imaging or proximalportion 690 of the catheter 605. The safety plug 646 provides moretensile strength for preventing the distal or RX portion 695 of thecatheter 605 from becoming detached from the imaging or proximateportion 690. As set forth above, the safety plug 646 may be added inaddition to the rotational bearing 626 shown in FIG. 5 for addedstrength or can serve in place of the rotational bearing 626 shown inFIG. 5, as shown in FIG. 6.

FIG. 7 is a side view of a manually steered RX catheter according to anembodiment of the invention. The catheter 705 in this embodiment allowsthe transducer assembly 730 to be rotated inside of a catheter body 725by a torque cable 740 similar to the torque cable 140 used in the priorart shown in FIG. 2. At the proximal end 741 of the torque cable 740 isan angle encoder 780 that measures the angular position of thetransducer assembly 730 and sends the information to imaging processingelectronics (not shown) proximal to the angle encoder 780. A torquinghandle 785 is provided which allows an operator to firmly grip theapparatus when rotating the torque cable 740 and transducer assembly730.

FIG. 8 is a side view of a manually steered IVUS catheter according toanother embodiment of the invention. The manually steered IVUS catheter805 of the embodiment of FIG. 8 is similar to the embodiments of FIGS.5-7 but discloses a rotary joint 826 between the distal or RX portion895 of the catheter 805 and the rotating imaging or proximal portion 890of the catheter 805. In this embodiment, the rotary joint 826 comprisesa ball and socket joint that connects the distal or RX portion 895 tothe imaging or proximal portion 890 which holds the transducer assembly830, including transducer 820. A ball 872, which in this embodiment is ahighly polished metallic ball, is attached to a wire 810 a that isjoined to the distal or RX portion 895. The ball 872 is captured withina socket 874, for example, a polymeric socket, attached to the imagingor proximal portion 890. One advantage of this embodiment is that a lowrotational friction rotary joint is obtained that allows flexure at therotary joint 826. Additionally, the wire 810 a can be ground to variousdiameters along its length to provide a gradually varying degree ofstiffness to minimize flexural discontinuities from the distal end ortip 815 through the rotational joint 826. The metallic ball 872 and wire810 a may be produced from materials, such as stainless steel andnitinol. The distance “A” between the two components 872 and 874 shouldbe minimized to reduce the possibility of capturing or snagging tissuewithin the artery or on exit or retraction at the tip of the guidingcatheter.

FIGS. 9A-9D detail a handle rotation mechanism 912 for rapidly spinninga catheter one or more revolutions with each activation thereof. Thatis, FIG. 9A is a perspective view of a handle rotation mechanism thatincorporates a pullback ratcheting mechanism according to an embodimentof the invention. FIG. 9B is a perspective view of a drive rollermechanism contained within the pullback ratcheting mechanism of FIG. 9B.FIG. 9C is a perspective view of the handle rotation mechanism of FIG.9A, showing an upper housing portion in place. FIG. 9D is a perspectiveview of the handle rotation mechanism of FIG. 9A, showing an angleencoder.

The handle rotation mechanism 912 may include an angle encoder 996, asshown in FIG. 9D. Each successive activation of the handle rotationmechanism 912 can reverse the direction of rotation of a catheter so asto prevent the electrical wires (not shown) of the catheter from windingup. In addition, the handle rotation mechanism 912 can be configured toperform a pull back ratcheting operation or imaging sequence. That is,each activation of the handle rotation mechanism 912 may not only rotatethe catheter, for example, ˜360 degrees, but may also pull the cathetera fixed distance, for example ˜0.5 mm, along a longitudinal axis of thecatheter.

The handle rotation mechanism 912 may be a one person, one hand operatedmechanism, which may be attached to a proximal end of a catheter. It maybe permanently attached or configured as a separate piece that isattached to the catheter just prior to or during a procedure. In oneembodiment, the handle rotation mechanism 912 is an integral part of thecatheter so that an interventionalist or operator does not have toassemble the system prior to use. One advantage of this embodiment isthat it provides a simple, low cost mechanism that is disposable after asingle use. The handle rotation mechanism 912 includes a handle body 901a, 901 b, which is attached to an outer sheath or catheter body 902 of acatheter. A rotating shaft 903 is attached to a rotation/translationmechanism within the handle rotation mechanism 912. The rotating shaft903 is attached to the catheter body 902 by means of shaft positionfitting 998.

A fluid injection port 993 a, as shown in FIGS. 9C-9D, may be suppliedat a junction of the catheter body 902 to the handle body 901 so thatthe space inside the catheter body 902 can be flushed initially andperiodically with, for example, heparinized saline, to initially preventair embolization and later prevent blood from filling the space andcompromising the materials' frictional and imaging properties.

The catheter body 902 may be a single lumen polymer extrusion, forexample, made of polyethylene (PE), although other polymers may be used.Further, the catheter body 902 may be formed of multiple grades of PE,for example, HDPE and LDPE, such that the proximal portion exhibits ahigher degree of stiffness relative to the mid and distal portions ofthe catheter body. This configuration provides an operator with catheterhandling properties required to efficiently perform the desiredprocedures. Additionally, the catheter body may be approximately 110 cmin length.

In this embodiment, squeezing a handle lever 904 causes the shaft 903 torotate, for example, ˜360 in one direction. A subsequent squeeze of thehandle lever 904 causes the shaft 903 to rotate, for example, ˜360 inthe opposite direction. The ˜360 degree rotation is given by way ofexample, as other degrees of rotation may be appropriate based on theparticular application. For example, different shaft stiffness andconfigurations for coronary and peripheral vascular system usage mayrequire the rotation mechanism to turn the shaft further than ˜360degrees to achieve ˜360 degrees of rotation at the distal end of thecatheter in-vivo.

The rotational motion of the shaft 903 is caused by the lever 904contacting a rotational first drive roller 991. As the lever 904 ismoved towards a centerline of the shaft 903 an inner surface of thelever 904 bears against the first drive roller 991. The drive roller 991may have a round, square, or other cross-section and may be made from anelastomer or other material that provides a high degree of frictionagainst the lever 904. When the lever 904 reaches the end of its travel,a trip mechanism (not shown) causes the lever 904 to shift position. Theshift in position causes the lever 904 to contact a rotational seconddrive roller 992. Releasing the lever 904 to its extended positioncauses the second drive roller 992 to freely rotate due to a clutchmechanism (not shown) within. The next push of the lever 904 causes thesecond drive roller 992 to rotate the shaft 903 in a direction oppositethe first drive roller 991. This process is repeated upon each press ofthe lever 904. The stroke of the lever 904 and the diameter of the driverollers 991, 992 may be chosen to accomplish the ˜360 degree rotation.As previously discussed, it may be advantageous to rotate the shaft 903further than ˜360 degrees or multiple times for imaging purposes. Insuch a case, the lever travel to roller diameter may be selected toachieve the desired rotation.

FIG. 9B discloses elements of the translation mechanism 914 of thehandle rotation mechanism 912 of FIG. 9A. That is, the drive rollers991, 992 may have an inner geometric cross-section, such as a triangle.The shaft 903 of the catheter contained within the handle rotationmechanism 912 may have a corresponding cross section sized to provideclearance within the roller 991, 992. This configuration allows therollers 991, 992 to drive the shaft 903 yet still allows fortranslational movement. As shown, steel balls 938 may be included toreduce the frictional properties of the shaft 903 sliding within thedrive rollers 991, 992.

The shaft 903 attaches to the handle rotation mechanism 912 using theshaft position fitting 998, as discussed above and shown in FIGS. 9C-9D,which allows a relative axial position of the shaft 903 versus thecatheter body 902 to be adjusted within a designed limit. The shaftposition fitting may be a plastic or metal collar or adjustable gasketthat can be tightened sufficiently to grip the shaft 903.

A switch 997, as shown in FIGS. 9A, 9C, and 9D, is provided on thehandle rotation mechanism 912 to change the mode of operation betweenrotation only and rotation with translation (pullback). The translationmechanism 914 causes a translation pinch roller 906 to bear on a surfaceof the shaft 903 and thereby sandwich it between the translation pinchroller 906 and a translation drive roller 907. The translation driveroller 907 is driven by rollers 908, 909, which in turn are driven bythe lever 904. By selecting and arranging different diameter rollers, aratio of lever movement to catheter translation may be designed.Further, the various rollers may be molded plastic with overmoldedelastomeric frictional surfaces.

The handle rotation mechanism 912 may incorporate an angular positionsensor 996, as shown in FIG. 9D, to provide catheter shaft rotationaldata to the ultrasound system. The angular position sensor 996 may beconfigured to directly read the angular rotation via an encoder wheel996 a attached to the catheter shaft 903 and optical encoder 996 bpositioned adjacent thereto, as shown in FIG. 9D, or indirectly viasensing the movement of the handle lever 904.

The foregoing describes a handle rotation mechanism configured to rotatea catheter in one direction directly followed by rotation in theopposite direction. However, it may be desirable to provide a mechanismthat allows repeated rotations in a particular direction. In thisinstance, the handle rotation mechanism may contain a clutch mechanismthat allows the handle rotation mechanism to return to its startposition, thereby allowing for multiple actuations in the samedirection. Further, a switch may be provided to change the direction ofrotation. Allowance for windup of the catheter electrical connection maybe provided by swivel connectors, such as a slip ring or inductiverotary electrical couplers.

The above described invention is directed to various embodiments of acatheter that permit an RX design to be used for a manually steered IVUScatheter. Such catheters, and their associated imaging systems, havesignificant cost advantages over both mechanically steered, motor drivenIVUS systems and electronically steered IVUS systems.

An additional advantage of the invention deals with reduction of motionartifacts that can occur with a manually steered IVUS system. Forexample, since the heart is constantly beating, and most vessels ofinterest have an open lumen diameter that is significantly larger thanthe diameter of the catheter, a manually rotated catheter can sufferfrom motion artifact. For example, if a complete ˜360 scan of an arterytakes ˜2 seconds to sweep out and in that ˜2 seconds, 2 or 3 heart beatsoccur, the relative motion of the catheter in the open lumen can createsevere artifacts in the image. This is a consequence of the fact thatthe position of the ultrasonic transducer relative to the vessel ischanging while the image is being swept out. By employing a handactivated mechanism that automatically spins the catheter ˜360 degreesin less than an ˜half second, the artifact can be removed orsubstantially reduced.

The foregoing embodiments and advantages are merely exemplary and arenot to be construed as limiting the invention. The present teaching canbe readily applied to other types of apparatuses. The description of theinvention is intended to be illustrative, and not to limit the scope ofthe claims. Many alternatives, modifications, and variations will beapparent to those skilled in the art. In the claims, means-plus-functionclauses are intended to cover the structures described herein asperforming the recited function and not only structural equivalents butalso equivalent structures.

1. A method of using a manually steered rapid exchange catheter toimage, diagnose, and/or treat an area of interest in a patient's body,comprising: introducing a guidewire to an area of interest in apatient's body; loading the manually steered rapid exchange catheter onthe guidewire, the manually steered rapid exchange catheter comprising:a proximal portion; a distal portion including a guidewire passagehaving both an entry and exit; an imaging, diagnosing, and/or treatingdevice positioned within the proximal portion, the device being manuallyrotated to affect steering of energy emitted by the device; and arotational joint that couples the distal portion and the proximalportion advancing the manually steered rapid exchange catheter along theguidewire to the area of interest; and manually steering the manuallysteered rapid exchange catheter by rotating the imaging, diagnosingand/or treating device contained within the proximal portion of themanually steered rapid exchange catheter, while maintaining the distalportion rotationally stationary, to image, diagnose, and/or treat thearea of interest.
 2. The method of claim 1, wherein the manuallysteering step comprises: manually steering the imaging, diagnosing,and/or treating device, by an operator, using a manual steering deviceattached to the imaging, diagnosing, and/or treating device.
 3. Themethod of claim 2, wherein the manual steering device is configured torapidly rotate the imaging, diagnosing, and/or treating device.
 4. Themethod of claim 2, wherein the manual steering device is configured totranslate the imaging, diagnosing, and/or treating device along acentral longitudinal axis of the proximal portion of the manuallysteered rapid exchange catheter.
 5. The method of claim 2, wherein themanual steering device is configured to: rapidly rotate the imaging,diagnosing, and/or treating device; and translate the imaging,diagnosing, and/or treating device along a central longitudinal axis ofthe imaging, diagnosing, and/or treating device.
 6. The method of claim1, wherein the manually steered rapid exchange catheter comprises anIVUS rapid exchange catheter.
 7. The method of claim 1, the device beingan imaging device.
 8. The method of claim 1, the device being adiagnosing device.
 9. The method of claim 1, the device being a treatingdevice.
 10. The method of claim 1, the rotational joint being arotational bearing.
 11. The method of claim 1, the rotational jointbeing a safety plug.
 12. The method of claim 1, the rotational jointbeing a rotary joint including a ball attached to a wire and capturedwithin a socket.
 13. The method of claim 1, the manually steered rapidexchange catheter comprising a torque cable upon which the imaging,diagnosing, and/or treating device is mounted, and the torque cablebeing arranged to rotate within a catheter body of the proximal portion.